The mechanism of translocation of proteins across specific intracellular membranes will be studied for secretory, lysosomal, peroxisomal, mitochondrial and membrane proteins. The proposed studies will utilize the in vitro translocation systems which have been developed in this laboratory (1) to determine the amino acid sequence of the "signal" of various representatives of the above mentioned groups of proteins, (2) to characterize and to purify the various specific membrane transport systems which recognize specific signals and effect translocation across the lipid bilayer of membranes, and (3) to characterize and to purify the specific "signal" peptidase which effect endoproteolytic removal of the signal following translocation across the membrane.